Integrated lead or wireless disk drive head suspensions are well known and disclosed, for example, in the Shirashi et al. U.S. Pat. No. 6,891,700 and the Bennin et al. U.S. Pat. No. 5,839,193. Theses devices generally include a flexure mounted to a spring metal load beam. The flexure typically includes a spring metal layer with a plurality of conductors or traces extending between terminal pads on opposite ends of the suspension. A layer of insulating material separates the traces from the underlying spring metal layer. A coverlay or cover coat layer is formed on the side of the traces opposite the insulating layer.
Subtractive and/or additive processes can be used to manufacture these devices. Subtractive manufacturing processes as disclosed, for example, the Bennin et al. U.S. Pat. No. 5,839,193 uses photolithography and etching processes to form the flexure from laminate material stock having a spring metal layer and conductor layer separated by an insulating layer. Additive manufacturing processes as disclosed, for example, in the Matsumoto et al. U.S. Pat. No. 5,666,717 use photolithography, deposition and etching processes to add the insulating layer, conductor layer and other structures to the spring metal layer.
The spring metal layer of the flexure acts as a ground plane for the traces. For a number of reasons, including the relatively thin nature of the insulating layer, the traces and spring metal layer can be electrically coupled. These electrical characteristics can reduce the signal performance characteristics of the traces. Approaches for compensating for the impact of the spring metal layer on the signal performance characteristics are known. For example, the Shirashi et al. U.S. Pat. No. 6,891,700 discloses holes through the spring metal layer of the flexure below the conductors to lower parasitic capacitance. In another example, the Morita et al. U.S. Pat. No. 6,380,493 discloses removing the coverlay from between adjoining conductive lines to reduce capacitance between the lines and improve the high-frequency characteristics of the circuit pattern.
There remains, however, a continuing need for integrated lead structures providing improved signal performance. To be commercially viable any such structures must be capable of being efficiently manufactured.